Exploration of the oxygen reduction reaction activity of four transition metal borates: synthesis, structure and characterization.

Abstract

Four new transition metal borates, [Co(1-MI)2]·B5O7(OH)3 (1, 1-MI = 1-methylimidazole), Co2(PZ)8(SO4)2·2H3BO3 (2, PZ = pyrazole), K7{(BO3)Co[B12O18(OH)6]}·H2O (3) and K2{[Ni(PY)2]2·[(C4H2O6)2B]}2 (4, PY = pyridine), have been successfully synthesized by a mild method. Their structures were determined by X-ray single crystal diffraction. These compounds were further characterized by FTIR, PXRD and UV-vis-NIR. It is worth noting that the catalytic properties of catalysts based on these four borates were explored, and that organically templated borate 1- and 2-based catalysts showed better ORR catalytic performance compared to 3- and 4-based catalysts. This may be caused by the supramolecular skeletons of 1 and 2 providing sufficient space and porosity.